In impact tools disclosed in the aforesaid patents, the energy stored in a spring is released to rotate an inertia or mass member which impacts against a tool head to rotate the latter when driving connections between the inertia member and tool head are brought into rotative alignment. In these devices, the inertia member is journaled on a cam which, in turn, is journaled on the tool head so that some of the spring thrust force is not only wasted, but imposes wear producing loads on the journal surfaces between the inertia member, cam and tool head. Also, as a result of the dissipation or wasting of some spring thrust force, such impact tools cannot tighten a fastener to the same degree as they might be capable of doing if there was not this loss of some of the spring thrust force. Therefore, these impact tools, to deliver impact forces of a specified magnitude, have to be made larger to compensate for the losses than would be required if those losses were substantially reduced. Also in the heretofore impact tools of the type shown in the cited patents, separate motion stops for limiting spring movement and rotation of the inertia member are required.
Accordingly, it is an object of the present invention to provide a manually-actuated, impact tool capable of providing greater impact force than impact tools of like type and of comparable size.
It is another object of this invention to provide a manually-actuated, impact tool of relatively simple construction, of high efficiency, and improved reliability.